1. Field of the Invention
The present invention relates to a rotary looptaker in a sewing machine, more particularly toan arrangement for avoiding trouble or problems due to friction caused by rotation between a looptaker and a bobbin case.
2. Description of the Prior Art
in a conventional vertically rotary looptaker according to which a looptaker is driven to rotate with an annular rib of a bobbin case fitted into an annular groove of the looptaker, the rotational speed of the looptaker is at most 7,000 rpm, since the loopertaker and the bobbin case are made of iron. Even in the arrangements wherein lubricant oil is supplied to the annular groove of the looptaker and the annular rib of the bobbin case, the rotational speed is yet at most 12,000 rpm. In such a conventional mechanism, although sliding resistance is reduced by the lubricant oil, friction is still produced between the annular groove of the looptaker and the annular rib of the bobbin case. Besides, the use of the lubricant oil brings about attachment of oil to the thread thereby preventing the sewing operation from being smoothly performed.